Truth about sytec

4 replies to this topic
  • cycleforfun

Posted October 24, 2006 - 06:02 PM


I have read that it is not advisable to run fully synthetic oil in the 4 stroke motocross bikes because they have a wet cluch and it will cause it to slip.

Since I have come to realize that this forum is full of good and reliable information, I thought I would ask if anyone on has used fully sytec in a thumper or known someone who has because some of these DO NOT's on the internet are just specualtion or wives tales.

The reason I ask is because I have 4 quaters of Repsol fully synthetic 10W-40 that I use for my GSXR-600 but since I am not going to be going back to the track untill the spring due to cold weather, I thought I would try to put it in the dirt bike I just bought. Is this seriously a bad idea?

  • buzzgrizz

Posted October 24, 2006 - 06:38 PM


I use fully sinthetic oil (10w 40 mobil one, just for thumpers) in my two bikes.
It will not affect the wet clutch system.

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • Fastest1

Posted October 24, 2006 - 07:36 PM


You must run the same API rating oil/synthetic lubricant as is recommended for that application. There are synthetics and oils that will contain friction modifiers, emulsifiers, anti foaming agents, and a variety of other additives that will cause a clutch to slip. In fact Yamalube 4R is a semi synthetic 10W-50 non friction modified lubricant. Look for a SH or higher non friction modified lubricant only.

  • jamiehughes

Posted October 24, 2006 - 07:50 PM


i run the full synthetic silkolene pro 15w40 in my 06, no problems as of yet, seems to work fine.

  • grayracer513

Posted October 25, 2006 - 08:47 AM


That's an old-school myth. The oils that MAY cause clutch problems are any that are graded API "EC II" (energy conserving II), and most oils that qualify as EC II are, in fact, synthetic. But it is NOT TRUE that most synthetics are EC II.

In fact, many that are marketed as motorcycle oils carry that JASO MA grade, which certifies compatibilty with wet clutches, and very few commercial (API C*) are ever EC II.



Related Content


yz250x vs 450 4t comparisons (preferably desert riding) needed by JakeNorthrupYZ450F

Dirt Bike   Make / Model Specific   Yamaha   Yamaha 2-Stroke
  • 9 replies

Is the 2016 GYTR Yamaha YZ450F too fast? by Fryboy

Dirt Bike   Special Interest Forums   Pro Racing
  • * - - - -
  • Hot  241 replies

Chubby dad, looking at bikes , First trip to the orange/black forum ! by Slow_ride

Dirt Bike   Make / Model Specific   KTM   250-530 EXC/MXC/SXC/XC-W/XCR-W (4-Strokes)
  • Hot  28 replies

yz400f throttle bog by yz400fmaniac

Dirt Bike   Make / Model Specific   Yamaha   YZ 400/426/450
  • * * * * *
  • Hot  28 replies

Need help by Goforaride

Dirt Bike   Dirt Bike Technical Forums   Suspension
  • Hot  68 replies

Join Our Community!

Even if you don't want to post, registered members get access to tools that make finding & following the good stuff easier.

If you enjoyed reading about "" here in the ThumperTalk archive, you'll LOVE our community. Come join ThumperTalk today!

The views and opinions expressed on this page are strictly those of the author, and have not been reviewed or approved by ThumperTalk.